The controls for the Slope are like this:
Q – E – you can use these two keys to steer the ball.
A – D – you can use these two keys to steer the ball.
Right and Left arrow keys – you can use these two keys to steer the ball.
There are no addition keys to control the ball in the game. You can use any of these three key combinations to play the game. If you are playing on a laptop, you might want to use Q-E and A-D as you might not have arrow keys.